Electric-arc lamp.



F. W. GORE. ELECTRIC ARC LAMP.

APPLICATION FILED MAY 2. 1906.

Patented May 18, 1915.

2 SHEETS-SHEET Wifnes; s

Fred- W- Gorey F. W. GORE.

ELECTRIC ARC LAMP.

APPLICATION FILED MAY 2. 1906.

Patented May 18, 191-5.

2 SHEETS-SHEET 2.

"IVE/ TOR fi'ed- W- Gore ITTURNEYS WITNESSES era. PAT

OFFICE.

FREDERICK GORE, OF NEW YORK, N. Y., ASSIG-NOR OF ONE-FOURTH T0 HARRY F.

ASBURY, OF BROOKLYN, NEW YORK, AND

HUNTINGTON, NEW YORK.

ONE-FOURTH T0 FRANK ASBURY, or

ELECTRIC-ARC LAMP.

Specification of Letters Patent.

Patented May 18, 1915.

Application filed-May 2, 1906. I Serial No. 314,785.

To all whom it may camera:

Be it known that I, FREDERICK.WHLIAM GORE, a citizen of the United States, residingat the city of New York, borough of Brooklyn, in the county of Kings and State of New York, have invented a certain new and useful Electric-Arc Lamp, of which the following is a specification.

This invention isan electric arc lamp designed for use on incandescent lighting circuits.

The. invention embodies improved mean-s for attaching an electric arc lamp to a lamp socket similar to an ordinary incandescent electric lamp, whereby the arc lamp of this invention may be used on incandescent lighting circuits.

The invention consists, also, in the provision of means, forming a permanent element of an electric arc lamp, for reversing the connections of the lamp in those cases where the polarity of the socket terminal does not correspond with that required by the lamp.

The invention consists, further, of an arc lamp having an inclosing globe constituting one chamber, another chamber in communication with the first chamber, a hollow solenoid plunger positioned for movement with-- ous contents of the globe become diluted by admixture with atmospheric air when the lamp is extinguished as by switching the current 01f for a few minutes, and then switching on the current. At such times, the admixture of air with the gases produces an explosive mixture in the arc inclosing globe, and should the current be switched into the lamp when such gaseous mixture is present in said globe chamber, the electric are produced by the separation of the carbons will ignite the gaseous mixture, thus resulting in an explosion which in some instances produces a shock-suflicient' to derange some of the working parts of the lamp.

The separate chamber employed in the burning,

not come into contact with the gases in the 4 are inclosing globe so as to produce the explosive mixture, nor do the diluted gases pass from the separate chamber into the arc inclosing globe until such gases contained in the separate chamber have become so diluted with atmospheric air that an explosion cannot take place in the arc inclosing globe when the arc is again struck.

For controlling the feed of the upper carbon, I employ mechanism which counter,

acts the force of gravity on the solenoid core and insures a gradual approach of the upper carbon toward the lower one for the purpose of restoring the are without mechanical contact between the carbons. Said mechanism in the present lamp is a combined dash pot .and retardation device which controls the gravity feed of the upper carbon. The mechanism is, furthermore, peculiar in the following respects: first, the dash pot is characterized by the employment of a single valve operating to control the inflow of air when the parts are moved suddenly by the first onrush of the current, and said valve acts to check the egress of air when the core falls by gravity, and, second, the dash-pot piston remains practically stationary while the cylinder ismovable, thus reversing the ordinary dash-pot mechanism.

My arc lamp is of such small dimensions that it is capable of attachment to the usual incandescent lamp socket, with practically no change in the construction thereof.

My new lamp is exceedingly compact, and

v the parts are so designed that they will oc- One form of my are My new lamp is especially intended for indoor lighting, to replace the cluster of incandescent lamps commonly used, but it is evident that it can be used with equal advantage in outdoor illumination.

Furthermore, a single lamp of my invention secures marked economy in the consumption of current as compared with a cluster of incandescent lamps capable of producing equal illumination.

Figure 1 is a vertical section, with parts in elevation, through an arc lamp embodying my invention, the lamp shown being substantially full size; Fig. 2 is an inverted or bottom plan full size view of the suspending plug shown by Fig. 1; Fig. 3 is a top plan view (full size) of an upper platform employed in the lamp above the magnet or solenoid; Fig. & is an elevation of the platform shown by Fig platform, the platform shown by Fig. 1 being inverted as compared with its position in the lamp as shown by Fig. 1; Figs. 5, 6

and 7 are detail full size views of my new clutch, showing the same in bottom plan, side elevation, and top plan, respectively; Fig. 8 is an enlarged detail view showing parts of the dash-pot and retardation device; Fig. 9 is a detail view through a series of three tubes employed in the lamp, two of said tubes forming parts of the dash-pot and retardation device; Fig. 10 is an inverted or bottom plan view of the disk or member from which is suspended the support for the lower carbon; Fig. -11 is a diagrammatic view of the circuit through the lamp. My new lamp has its working parts housed within an external casing 5, the latter being of any suitable form and material, and also being, preferably, open at its respective e ds.

A flanged ring 6 is positioned around the lower part of easing 5, said ring serving as a seat for the edge portion of a globe 7, said edge of the globe being fitted within the flanges of the ring and said globe having engagement with one of said flanges, substantially as shown by Fig. 1. The ring 8 is positioned upon above the ring 6, said ring 8 being secured in place on the casing by any suitable means, such, for example, as the screws 9. Said ring 8 is deflected or inclined outwardly intermediate its ends, so that the lower part 8 of the ring is of greater diameter than the upper part thereof, whereby the upper art 8 of the ring is adapted to embrace, and to be secured firmly to, casing 5, while the lower and enlarged part of the ring fits around, and extends below flanged ring 6, see Fig. 1. In the enlarged lower and free art of the ring 8 are the clamping screws 10, the latter engaging with the globe 7, and adapted to hold the latter firmly in place.

. 3, and showing the full size of said the casing 5, at a point r The lower'casing 11 is positioned, at its upper portion, within the lower open end portion of easing 5, and, also, inner flange of ring 6, said casing 11 being attached in a suitable manner to the ring, so as to be held in position thereby. The casing 11 extends into the upper'part of globe 7, and the end portions of said casing 11 are closed by means of the plates or disks 12, 13, the same being made, preferablyof mica, or any other appropriate insulating material, suitable for the purposes of my lamp.

Obviously, the'casing 11 may be secured to ring 6 by screws or rivets (not shown), and as ring 6 is connected to casing 5, it is evident that the casing 11 is connected to casing 5 by means of said ring 6. The plate or disk 13 engages with the lower part of a solenoid 14 the latter being housed within casing 5. The other disk 12 is fitted to the lower part of the casing 11, and is clamped against the edge portion of said casing by a suitable ring 15, the latter serving to secure tight joint between the disk 12 and the' caslng 11.

The casing 11 and disks 12, 13, form a substantially closed gas chamber 16, said chamber being positioned substantially between the globe chamber and the chamber provided by easing 5 The disk 12 which forms the bottom of chamber, 16, is provided with a bushing, 22, through which the upper carbon, A, is adapted to pass, and this bushing establishes communication between chamber, 16, and the chamber, 7, of globe, 7. The disk, 13, forms the top wall of chamber, 16, and in the center of said disk, 13, is an opening in which the member, lt, of a plunger is adapted to work. The opening in disk, 13, is nearly filled by plunger, 14", but it is evident that pir can enter chamber, 16, through said opening in disk, 13, although theinflow of air or the outflow of gases from said chamber, 16, takes place in very limited quantities. It will be observed that the globe 7 provides a chamber 7 the carbons A, B, are arranged to produce the electric arc, the gases resulting from the production of the are being collected by or within the chamber 7 and more or less of said gasesflow from said chamber, 7 into the diluting and collecting chamber, 16. The chamber 16, which is formed by the casing 11, and the disks 12, 13, is separate from the chamber 7 of the globe, and in this chamber 16 is adapted to be stored some of the gases which result from the arc. The lower or negative carbon B is fitted in a socket at the lower part of the metallic yoke 17, the latter being attached to, and suspended from, the insulating disk or plate 12 at the bottom of the gas chamber 16.

It is preferred to make the legs of the within the within which y attests metallic contact a wire 21, which platform being obvicuslysecured to the easforms a part of the negative lead of the lamp, the current flowing through the negativ'e carbon, the yoke, one of the thimbles 1-8, and the conduct r 21.

Extending upwardly from the member 13 is a staticnarytube 22, around which is coiled the solenoid 14, the flatter being covered as usual with a propriate material which is engaged by screws 9, said screws being supported in casing 5 and operating to retain the magnet in a fixed position therein. The magnet or solenoid extends upwardly from the member 13, so as to occupy, practically, the whole space within -the casing 5,a1 1d between said member 13, and an insulating platform 23, the latter made of porcelain, fiber, or any other epprepriate insulat ing material. This latform 23 occupies a stationary position within easing 5, said The ing by suite-h screws (net shown).

platform is positioned casing 5, close to th upper open end thereof and above the solenoid 14, the upper end 'o'f'the tube 22 being fixed to said platform in any approthe upper side of the a't' form 23 are parallel priate way.

On the under side of the platform is supported a non-metallic resistance 24, the same consisting of any suitable material, such as carbon, adapted to answer the.purpose, and

being of any appropriateshape and dimensions. The resistance '24 is fitted against j the platform 23, and attached thereto by suitable screws, one of which is indicated at 58, in Fig. 3. The resistance is in the positive lead of the lamp, so as to be between the positive contact and the magnet '14:. On

ribs or flanges 2'6, 2 the being disposed on the respective sides of the opening 27*, for the tube 22, 'see Fig. Between the flanges 26 is a metallic plateQB, which is secured in place by a 29. Another plate 30 is held between the other pair of flanges 27 by a screw 31, and these two plates 28, 30, have upstanding members which are adapted for engagement with other plates 32, 33, respectively. Said plates 32, 33, are secured to a plug 34, which is provided with male threads, and is adapted "to be screwed ihtoa socket 35 1), which is included in an incandescent lighting circuit 36. The plug 34 has an integral head 34, and said plug is, furthermore, provided with a cavity or chamber 35. The metallic plate 32extend'salong the bottom face of the head 34, thence lengthwise of the plug within the chamber 35 thereof, and along the bottom face of the end portion of said plug 34:, at

which point a screw 36 is attached to said plate 32, for the purpose of making connection therewith from one contact 37 of the lamp. The plate 32, within the chamber. 35*, of the plug, is insulated electrically at 32*, see Fig. 1, from contact with the metallic parts of a combined retardation tube and dash-pot, to be presently described. The other plate 33 is secured on the lower side of the head 34* of the plug by ascrew 39, the latter having engagement with an exposed metallic plate 38, forming the other contact for the "lamp. The two plates '32, 33, have dependin members adapted to lap the up standin members of the plates 28, 30, and said members of the four plates are, conrigfted detachably together by screws 40, W

e'reby the plates 32 and 33 are adapted to* form one pair within the lamp,-and the other plates 28, 30, fo m another pair of plates within the lamp. Suitable holes or slots providedin the casing 5 opposite to the QCi'eWsAO, (see Fi 1) thus permitting a driver, or ot er implement, to be introduced into the lamp for the purpose of releasing the screws 40, and uncoupling the two pairs of plates 28, 32, and 30, 33, whereby the plug 34 may be detached and reversed, for the purpose of bringing the plate 32 into engagement with the plate 30, and the plate 33 into eng gement with the plate 28, thus making provision for reversing the leads or connections of the lamp relative to the incandescent circuit.

The plugfia provides a convenient means for interposing the arc lampin an incandescent circuit, because this plug is adapted to be screwed into the socket 35, so as to bring the two contacts 37, 38, of the lam into electrical engagement with correspon in" contacts of the socket 35, in a manner 76%1 understood by those skilled in the art of electric lighting.

The plug 34 with contacts 37, and lates 32, 33,- attached rigidly thereto, 1s umtary in construction, thus enabling said plug,

the plates and'the contacts to be handled and manipulated as a single element when it is desired to reverse the damp connections.

The plug thus performs a two-fold function, first, as a hanger for the lamp, and second, as a means whereby the lamp connections may be reversed. The plug '34 serves the purpose of a hanger for suspending the. arc lamp from the socket, and it is evident that the lamp can be easily removed by simply unscrewing the plug from the socket, and, f

furthermore,.that the lamp can be easily and quickly replaced, by simply screwing theplug into the socket.

The plunger 14 is a hollow cylindrical mass of soft iron arranged to have endwise movement within the tube 22, and the coil or magnet 14, and through this plunger passes the positive carbon A, the latter being of less diameter than the bore of the plunger, so as to play easily therein. A metallic tube 41 and the plunger lap each other, and are connected together, for simultaneous movement, by suitable pins or studs 42. The tube 41 passes through and beyond the tube 22 and the platform 23, so as to extend into the chamber or cavity of the plug 34. Within the upperpart of the tube 41 is placed a double acting valve, thus making a combined retardation device and dash-pot. The tube 44 is housed within the tube 41, and it is open at its lower end, for the free reception of the carbon A, the latter being thus adapted to pass through the hollow plunger, the tube 41, and into tube 44, as shown by Fig. 1, whereby a compact construction of lamp is secured. The upper part of the tube 44 has a head 44, which closes the upper end of the tube 44 (see Fig. 8). Within the upper end of the tube 41 is secured another head 45, the latter being provided with an air opening and a valve seat. Above the head 45 is a disk 46, having another air opening 47 and a valve seat, the latter beingon the under face of the disk 46. Between the head 45 and the disk 46 is a check valve 48, which is adapted to occupy one or the other of the valve seats, said seats being provided in the opposing faces of the head 45 and the disk 46.

The moving tube 41 is provided intermediate its ends with longitudinal slots 66, see Fig. 9, and through these slots extend screws 65, said screws being supported in bracket lugs fixed to the under side of platform 23. The screws engage firmly with the non-sliding tube 44, for the purpose of holding said tube 44 and its head 44 in a stationary position. By providing slots in tube 41, said tube" is adapted to move with plunger 14 and to' impart movement to heads 45, 46, relative to the head 44 of tube 44. It is to be understood that tube 44 and its head 44 constitute the piston member of the combined retardation device and dash pot, the moving members thereof being the tube 41,

heads 45, 46, and valve 48, said moving mem-- .bers being actuated directly by plunger 14.

.50 designates a clutch adapted to engage with the upper carbon A, for the purpose of controlling the gravity feed thereof. This clutch is represented'by Figs. 5, 6 and 7 in the form of a split ring, preferably made from sheet metal, by stamping the same.

Clutch ring 50 is shown as having a radial slot 51, see Figs.:5 and'7, the purpose, of

which is to enable an operator to so bend a part of the ring that the edge will bite against the carbon, but for the purpose of illustration in Figs. 5, 6 and 7, I have shown all parts of said ring in the sameplane. The clutch is provided with an upstanding arm, 52, which is pivoted by a pin 54 to a clutch carrier 53, see Fig. 6. The clutch carrier is in the form of a ring or collar having a female thread, and a rearwardly extending arm, the latter being indicated at 55. The carrier is screwed on to a threaded lower portion 14 of the plunger 14, whereby the clutch carrier is attached rigidly to said plunger so as to be supported directly there-' on, and to be movable therewith. The arm 55 of the clutch carrier provides for the pivotal attachment of the clutch 50 to said carrier, and said arm 55 also serves as a support for a spring 56, the function of which is to primarily prevent the clutch from being thrown out ofgripping engagement with the carbon A at the time when the current is first admitted to the lamp. As shown in Figs. 5 and 6, the spring is fastened to the arm of the clutch carrier. Said spring acts against the upper end of the clutch arm 52. By providing the clutch with the arm 52, andipivoting said arm to the clutch carrier at a point above and to one side of the vertical plane of the clutch ring, said clutch is made to tilt or drop to an inclined position slightly away from the carbon so that the ring will bind or impinge against said carbon, thereby securing the desired frictional engagement of the clutch with the carbon. By pivoting the clutch as described, and employing the spring 56, the clutch is held in engagement with the carbon firmly during the first onrush of the current, whereby the clutch 'isnot disengaged from the carbon under the conditions recited, nor will thecarbon be accidentally released from the clutch. The spring 56 does not control the clutch throughout the range of its movement, but the function of the spring is largely to overcome the sudden movement of the clutch when the current is first admitted. The carrier 53 and the pivoted springpressed clutch 50 are movable with the plunger 14, but the downward movement of the plunger is limited by a short post 57, the latter being attached to the arm 55 of the clutch carrier and extending downwardly therefrom, so as to have engagement with the plate or member 12, when the plunger reaches the limit of its downward movement.

sure within i-eases positive contact 37, the current is adapted to pass into the lamp through the screw 36*, the plate 32, the screw 40, the plate 28, and thence across by a wire. 57 to a screw 58, (Fee Fig. 3), through the resistance 24, by t e wire 59, to the screw 25, thence through v the magnets to a screw 65, and thence by a screw 65, into the tube 44. From the head 44 of this tube extends a flexible conductor 61, which is attached to the carbon carrier 62, the latter engaging with the upper carbon A. The current traverses the negative carbon B, one leg of the yoke 17, one socket 18, the screw 20, and the negative lead 21, the latter being attached, by a screw 63, to the platform 23 (see Fig. 3). From this screw 63 leads a conductor 64 to the negative contact 30, whereby the current is adapted to pass through said contact 30, and the screw 40 to the plate 33, the screw 38 and the contact 39.

In striking the arc, when the current is first admitted to the lamp, the flow of the current through coil 14 energizes the latter to establish a magnetic field. Prior to .switching on the current, plunger 14 and the parts associated therewith, occupy their lowermost positions, but when the magnetic field is established, by energizing coil 14, as previously stated, said plunger is drawn upwardly into the coil. This initial upward movement is a comparatively quick or sudden one, and this movement is communicated by the plunger to tube, 41, heads, 45, 46, and valve 48, the latter being confined between heads 45, 46. The quick movement of tube 41 and heads 45, 46 relative to the head 44 of stationary tube 44 decreases the air presthe dash pot chamber (formed by tubes 41, 44, and heads 45, 44 to a point below atmospheric pressure owing to the increase in the cubical area of the dash pot chamber bythe relative movement'of tube 41 to tube 44, thus establishing a artial vacuum in the dash pot chamber. he difference in pressure of the air in the dash pot chamber and the air at atmospheric pressure tends to force valve 48 to its seat in head 45 on the upward movement of tube 41 and heads 45, 46 with plunger 14', and thus the rapid inflow of air at atmospheric pressure to the dash pot chamber is'precluded, whereby the continued quick upward movement of the plunger is checked by the action of the dash pot mechanism.

When the strength of the current in coil 14 decreases, owing to an increase in the res stance of the are due to partial consumption of the carbons, the plunger 14, tube 41, and heads 45, 46, of this lamp have a tendency to descend quickly, owing to the fact that these parts are rather heavy. This tendency is, however, checked, and to a marked extent, by the action of this mechanism, which for convenience in designating it, I have termed a retardation device as well as a dash pot mechanism, for the reason that said device operates to materially lessen the speed of descent of plunger 14, and the tube .41. Upon the downward movement of atmospheric pressure, At first, the air escapes through the ports in heads 45, 46, but as the air pressure increases within the dash pot chamber, valve 48 is lifted by the increased air pressure so as to close port 47 in headi46, thus confining the air in the dash pot chamber. The air confined in the chamber serves as an elastic cushion to the movement of plunger 14 and tube 41, so that the plunger cannot descend rapidly, and thus the plunger moves downwardly at slow speed, so as to make carbon, A, gradually approach B for the purpose of bringing their ends into such close relation, but without coming into actual or mechanical .contact, that the current can fiow from one carbon to the other in order to restore the arc.

By reference to Fig. 1 it will be noted that tube 22 is open at both ends, the lower end of said tube being in communication with gas diluting chamber 16 and the upper end of the tube opening into the chamber of easing 5 formed between platform 23 and head 34 of the attaching plug A 32, said chamber being in communication with the outside atmosphere by holes or slots provided in casing 5 opposite to the screws 40. Furthermore, hollow plunger 14 operates partly within said diluting chamber 16 so that a part of the gases in said chamber 16 may flow upwardly between tubes 41, 42 into the atmosphere through the chamber between plug 34 and platform 23 and the apertures in the casing 5.

Air can flow slowly into chamber 16 through the path above described for the purpose of dilutingthe gases in said chamber 16, but as the chamber 16 is intermediate the air inlet and the arc-inclosing globe, atmospheric air cannot flow directly into the latter chamber, but any infiowing air first mixes with the gases in chamber 16 so that thegases insaid chamber 16 become diluted with air, and the mixed air and gases can, under certain conditions, flow from chamber 16 into the arc-inclosing chamber.

Changes in the form, size, proportion, and

being relatively adjustable one to the other I whereby the circuit terminals may be reversed with relation to the circuit contacts.

2. In an arc lamp, a casing, a hanger plug attached to said casing, circuit terminals on said plug, a platform positioned within the casing, and contacts supported on said platform and cooperating with said circuit terminals, said hanger plug and the circuit terminals thereon being reversible with reference to the platform and the contacts thereof.

3. In an arc lamp, a casing, a hanger plug attached to said casing, circuit terminals on said plug, a supporting member in fixed position within said casing, and contacts carried by said supporting member and cooperating with the circuit terminals, whereby the relation of the circuit terminals may be reversed to the contacts by changing the position of the hanger plug.

l. In an arc lamp, a casing, a hanger plug attached to said casing, circuit terminals on said plug, contacts supported on the hanger plug and positioned within the casing, a supporting member within said casing and below said hanger plug, and other contacts carried by the plug, said second named contacts having detachable engagement with the contacts of the hanger plug.

5. In an arc lamp, a casing, a hanger plug detachably fastened to the casing and adapted to be reversed thereon, exposed circult terminals on said hanger plug, contacts secured to the hanger plug and positioned within the casing, a platform fixed in said casing below the hanger plug, other contacts carried by the platform, and means for detachably connecting the contacts of the platform with the contacts of the hanger plug.

6. In an arc lamp, a casing, a platform therein, contacts carried by the platform, a unitary hanger reversibly connected to the caslng, other. contacts carried by said hanger and movable therewith, and means for rigridly connecting the two sets of contacts. In an arc lamp, a casing, a solenoid, a set of contacts fixedly supported within said casing and connected with said solenoid, a unitary hanger reversibly attached to the casing, and; another set of contacts carried by said hanger and coopera ing with the first named contacts, said h nger and the contacts thereof being reversible relative to the casing and the first named contacts therein.

versible with relation to the lamp, and con tacts reversible with said plug relative to the aforesaid contacts.

9. An arc lamp having a platform, a solenoid therein, contactssupported by said platform and in series with the solenoid, a unitary hanger so connected to the lamp as to be reversible with relation thereto, and contacts supported by the hanger and reversible therewith relative to the first named contacts.

10. In an arc lamp, a platform provided with contacts, a hanger reversibly connected to the lamp, and other contacts attached to the hanger, said contacts of the hanger cooperating with the contacts of the platform so that a reversal of the hanger will reverse the relation of the contacts.

11. In an arc lamp, a solenoid plunger, a platform, a clutch-carrier on said plunger, a stop member extending from the clutchcarrier and adapted to engage said platform for limiting the descent of said plunger, a ring clutch having an arm pivoted to the aforesaid carrier and positioned for engagement with the platform when the stop member contacts therewith, whereby the clutch releases a carbon as the stop member arrests the descent of the plunger, and means acting on the pivoted end of the clutch to retain it in engagement with the carbon when the plunger is lifted'to raise said clutch free from the platform, said stop member being in the path of the pivoted clutch and operating to limit thepivotal movement of said clutch under the pressure of said retaining means.

12. In an arc lamp, a solenoid plunger, a

platform, a clutch-carrier on said plunger, a rigid stop member depending from the clutch-carrier and adapted to engage with said platform for arresting the descent of the plunger, a ring clutch movable with the carrier and positioned for engagement with the platform prior to the engagement of the stop member with said platform, said ring clutch having an upstanding arm pivoted to the clutch carrier and means engaging the pivoted end of the clutch when the latter is lifted free from the platform and acting to hold said clutch in an inclined position, whereby the clutch is retained in engagement with the carbon when the plunger is "lifted during the first onrush of current a stop member depending from the clutchcarrier and adapted to engage with said platform for arresting the descent of the plunger, a clutch provided with an upwardly extending arm which is pivoted to the rear part of said clutch-carrier, said clutch having a ring or eye which is adapted to contact with said platform prior to the engagement of the stop member therewith, and a spring acting on the pivoted end of the clutch for retainingit into engagement with the carbon when the clutch is lifted free from the platform by the upwardmovement of the plunger, said stop member being in the path of the pivoted clutch 'and operating to limit the pivotal movement of said clutch under the pressure of said spring.

14. In an arc lamp, a solenoid plunger, a stationary platform, a stop movable with the plunger and adapted to engage said 7 platform, and a pivotedclutch, the movement of said clutch when free from a carbon being limited by said .stop.

. 15. In an arc lamp, a solenoid plunger, a swinging clutch movable therewith,'and a stop movable with the plunger and operating to limit the endwise movement of the plunger, and, also, to arrest the swinging movement of the clutch when free from engagement with a carbon.

'16. In an arc lamp, a carbon clutch composed of sheetmetal and comprising an upright member and a single eye or ring extending at an angle from said upright member, said eye or ring being split by a radial slot andone part of the said eye or ring being adapted to be deflected out of the plane of the other part of said ring.

17. In an arc-lamp, a solenoid, a plunger movable therein, and a combined retardation device and dash-pot cooperating with said plunger, said retardation device and dash-pot comprising a movable cylindermember attached to the plunger and provided with a head having upper and lower air ports, a fixed piston member within the movable cylinder member, and a single valve adapted to be seated by the pressure or suction of the air in thedash-poh and to open and close the upper and lower air ports in the head of the movable cylinder member.

18. In an arc-lamp, a solenoid, a plunger movable therein, and a combined retardation' device and dash-pot cooperating with said plunger, said retardation device and dash-pot comprising a movable cylinder member-attached to theplunger and provided with a head having upper and lower air ports, a fixed piston member within the movable cylinder member, said piston member having a tubular body and a head, the latter being opposite to the head of the cylinder member, and a single valve cooperating with the upper and lower air ports in the head of the movable cylinder member, the cylinder member and the tubular body of the piston member being adapted to re-' ceive the upper part of the upper carbon.

19. In an arc-lamp, a solenoid, a hollow plunger, and 'a combined retardation device and dash-pot cooperating with said plunger, said retardation device and dash-pot comprising a tubular cylinder member and a tubular piston member each adapted to receive the upper part of a carbon which passes through said plunger, said cylinder member and the piston member having opposing heads, the'head of the cylinder member being provided with a valved air port.

20. In an arc-lamp, a solenoid, a plunger composed of a hollow mass of metal, a movable cylinder united to the upper part of the plunger, said cylinder being closed at its upper end by a head having a port, a single valve controlling said port and operated solely by the pressure or suction of air in the movable cylinder, and a stationary tubular piston within the cylinder and provided with an imperforate head in opposing relation to the valved head of the cylinder.

21. In an arc lamp, a hollow solenoid plunger, a fixed tubular piston member in line with the plunger, and a cylinder member coupled with the plunger, said cylinder member being movable with respect to the piston member and provided with a single valve for controlling the passage of air single valve carried by the cylinder memberand adapted to control both the ingress and egress of air to the cylinder member.

23. In an arc lamp, a stationary tubular piston-member closed at one end, a carbon adapted to pla therein, a movable cylinder member provided in a closed end with facing valve seats, and a single valve adapted to occupy one seat or the otheron a relative movement of the cylinder member to the piston member.

24:. In an arc lamp, a stationary 'piston member, a solenoid plunger, a movable cylinder member closed at oneend and coupled with said plunger ,for movement therewith, said closed end having facing valve seats, and a single valve adapted to occupy 

